The short answer is yes.
For a longer answer, consider how the game has changed in the past few years. Hitting is down, way down. Scoring runs is tough for every team. And, for the As, scoring is really tough. This leads to a lot of close games. So far this month, 16 of their 23 games were decided by three runs or fewer. Unfortunately, the As have 5 wins and 11 losses on those games.
I used to subscribe to the conventional "Moneyball" belief that a manager really didn't matter all that much. Put in a reasonable lineup, manage the starters and bullpen, keep the players rested and on an even keel, and wait for the three run homer. Don't micromanage, don't call for bunts, don't risk giving up outs with steals and hit-and-runs to score a single run.
This strategy doesn't hold true for the Athletics this year. They seldom put up crooked numbers anyway, so giving up an out to try to put up a single run will seldom hurt, and might help. Much like running on a 3-2 count with two outs. If Coco is caught on a botched hit-and-run with Barton at the plate, what's the big loss? It's not like Barton is Joey Votto or Jose Bautista. The As must micromanage, and try more of those "clever", "overmanaging" things for which Tony LaRussa, Mike Scioscia etc. are notorious.
Look at how Bruce Bochy does it across the Bay. Frankly, I'm amazed at how well many of his moves work out. He puts in Schierholtz for defense late in a game, and almost immediately there's a screaming drive into the archways that he flags down. Now, much of this is probably blind luck, but, as Napoleon (supposedly) said, he'd rather have a lucky general. Whatever, his moves work, the Giant's players believe in his moves, and they pull out a lot of close games.
We could debate the merits of Bob Geren as an old-style "don't manage too much" manager. He seems to have problems with closers (Fuentes and Street). Others seem to have no problem with him. But that doesn't matter. I see no evidence that he has any skills at micromanaging, and plenty of evidence that he completely lacks those skills. Said skills are more important nowadays with the general dearth of hitting, and essential for the As.
Need I say it? Geren must go.